1. Field of the Invention
The present invention relates to a device and method for synthesizing a transmission frequency (a Tx frequency) in a wireless terminal. More particularly, the present invention relates to a device and method for synthesizing a Tx frequency in a wireless terminal, which is designed for stably operating a Phase Locked Loop (PLL) in order to synthesize a Tx frequency for a certain channel.
2. Description of the Related Art
In a Global System for Mobile communication (GSM) wireless terminal circuit, a Radio Frequency (RF) transceiver operates a PLL system so as to synthesize a Tx frequency for a certain channel. It always takes time to stabilize the PLL system and generate a first transmission burst (a Tx burst), that is, a Tx Ramp-up period is required, and a base band unit usually provides the RF transceiver with an IQ dummy signal so as to ensure the time.
Usually, a fixed output duration of an IQ dummy signal at a base band unit and a fixed synthesizing duration of a Tx frequency at an RF transceiver are assigned according to each manufacturer.
However, when the wireless terminal requires a Tx frequency, and the base band unit cannot provide the RF transceiver with an IQ dummy signal for a sufficient time, the RF transceiver cannot properly synthesize a frequency, and thus cannot stably carry a transmission burst for a required certain channel. In this case, there will be some failures in planned interface design between a base band unit and an RF transceiver, and thus a base band chipset or an RF chipset intended for use may be useless.